Machines such as, for example, backhoes, excavators, dozers, loaders, motor graders, and other types of heavy equipment use multiple actuators supplied with hydraulic fluid from an engine-driven pump to accomplish a variety of tasks. The actuators (e.g., hydraulic cylinders and motors) are used to move linkage members and tools on the machines including, for example, a boom, a stick, and a bucket. An operator controls movements of the actuators by moving one or more input devices, for example joysticks. Joystick movement manipulates a control valve associated with each actuator to control movement of the boom and stick to position or orient the bucket to perform a task. Typical operator control permits individual controlled movement of each linkage member with a corresponding operator input device, for example, along a specific input device axis. That is, each linkage (e.g. boom, stick, and bucket) is controlled by movement along a specific input device axis of one or more joysticks.
Typical operator control suffers several drawbacks due to the complex coordination required to maneuver the work tool, especially when the work tool attached to a linkage system that allows work tool movement about three or more degrees of freedom. For example, when moving the bucket along a predefined trajectory, the operator must continuously manipulate the joysticks to complete the task. As a result, some tasks may require a high level of skill that must be learned through experience. Even experienced operators may lack the necessary skill to precisely complete complex tasks. Further, operators of all skill levels may become inefficient due to fatigue or boredom when completing routine or repetitive tasks.
One example of an improved system for controlling a machine tool is described in U.S. Pat. No. 6,968,264 (the '264 patent) issued to Cripps on Nov. 22, 2005. The '264 patent discloses a machine including a mechanical arm having a first segment, a second segment, and a tool segment. Each segment pivots about a joint and is moved by one or more actuators. The '264 patent further discloses a system for controlling the mechanical arm by defining a planned path and automatically correcting an actual path of the mechanical arm when it is detected that the actual path differs from the planned path. For example, automatic correction may overcome inefficient movement by the operator due to operator fatigue or sloppy operating commands. The planned path may be stored in a library of planned paths and may be selected based one or more of the following factors: the geometry of the mechanical arm, the planned work task of the mechanical arm, the identity of the machine to which the mechanical arm is operably connected, and an optimal or preferential path of a skilled experienced operator of the machine or mechanical arm.
Although the machine of the '264 patent may improve operation efficiency by automating portions of complex tasks, it may be inefficient and have limited applicability. The machine of the '264 patent may be inefficient because it fails to consider the type or size of tool being used to complete the task. Without considering the type or size of tool being used, the desired tool path may not be as efficient as possible. Additionally, although it may help ensure the mechanical arm follows a particular path, the '264 patent may be limited because it fails to simplify typical complex operator input controls used to position the mechanical arm.
The disclosed control system is directed to overcoming one or more of the problems set forth above.